1. Field of the Invention
The present invention relates to an infant swing apparatus, and more particularly to a motor-driven swing apparatus.
2. Description of the Related Art
Caregivers usually rely on a swing apparatus to facilitate the care of an infant or young child. The swing apparatus can be used to provide a comfortable, safe and entertaining environment to the child. Conventionally, a swing apparatus is made up of a seat that can securely hold the child, and a frame having swing arms from which the seat is suspended. The swing arms are pivotally connected to the frame so as to be able to swing the seat back and forth.
A conventional drive system of the infant swing utilizes a gear reduction system that is coupled between an electric motor and a pivot shaft of the swing arm. More specifically, a control voltage is usually applied to the motor so as to drive it in the correct direction and at the correct velocity and torque. In turn, the gear reduction system can change the high speed and low torque of the motor into a rotation and torque capable of swinging the seat in a pendulum motion. In order to properly reverse the swing motion, a sensing device is used to determine the swing speed and amplitude. For this purpose, an infrared or other sensing device can be provided to monitor the rotation of an encoder wheel mounted on the motor shaft. As the swing motion approaches a speed of zero and then accelerates in the opposing direction, the encoder wheel can exhibit a corresponding change.
A problem with the aforementioned design is that the gear box typically has multiple gear stages for applying the correct reduction. Each of these stages introduces some backlash into the drive system. In particular, the backlash can create a situation where the swing motion has changed direction, but the change in direction is not instantaneously captured by a change in direction of the encoder wheel. Since the swing motion is continually changing directions, this issue can result in an incorrect determination of the swing amplitude and/or change in direction. Therefore, driving signals may be incorrectly applied to the electric motor.
Therefore, there is a need for an improved swing apparatus that can drive swing motion in a more accurate and efficient manner, and address at least the foregoing issues.